I made a program a week or two ago to draw a circle in BASIC using only integers and Pxl-On(). You could change Pxl-On() to Pxl-Change() or Pxl-Off() to draw different types of circle. I didn't check if it was any faster or slower than the OS routine, but this is more like PxlCirc or something:
I am pretty sure using decimals would have slowed it down quite a bit and I am pretty sure it can be made faster using some BASIC trickery. I basically used an algorithm that I came up with in assembly and since assembly is only integers, that is what I used here.